It is known that the anti-bacterial spectrum and pharmacological properties of many naturally produced aminoglycoside antibiotics can be altered by structural modifications. For example, certain chemical modifications in the gentamicin and kanamycin family of aminoglycoside antibiotics provide structures which are less toxic than the parent antibiotic. Further, certain chemical modifications in the above family series alter the antibiotic spectrum advantageously either by increasing the intrinsic activity or increasing their activity against resistant strains.
Recently, a new family of aminoglycoside antiobiotics, the fortimicins, has been identified. See U.S. Pat. Nos. 3,976,768 and 3,931,400 which disclose the naturally produced parent antibiotics, Fortimicin A and Fortimicin B.
Historically, once an aminoglycoside antibiotic has been in clinical use for awhile, resistant microorganisms arise. In many cases, the resistance is R-Factor mediated and is attributed to the ability of the bacteria to enzymatically modify the amino or hydroxyl groups of the aminglycoside antibiotic. It is known that in the naturally occurring fortimicin aminoglycoside antiobiotics, blocking the hydroxyl group inactivates the antiobiotics.
The present invention provides 5-deoxyfortimicins and 2,5-dideoxyfortimicins which could not be inactivated by R-factor carrying microorganisms which could modify the hydroxyl groups of the parent fortimicins.